Automatic tandem drum paver



Feb. 13, 1934. E H, UCHTENBERG 1,946,944

AUTOMATIC TANDEM DRUM PAVER Filed Oct. 6, 1930 Sheets-Sheet 1 mfmnmu WAN www U\%\ Feb- 13 1934- E. H. LICHTENBr-:RG

AUTOMATIC TANDEM DRUM PAYERl 4 Filed oct. 6, 19:50

2 Sheets-Sheet 2 Patented Feb. 13, 1934 PATENT- OFFICE AUTOMATIC TANDEM DRUM PAVER rich H. Lichtenberg, Milwaukee, Wis., asslgnor to Koehring Company, Milwaukee, Wis., a corporation Application October 6, 1930.

4 Claims.

This invention has to do with the art of conqrete mixing machines, and particularly to such machines when used in connection with concrete making operations, the specifications for which require the mixing of the aggregates of the concrete for predetermined periods of time. An example of such machines, is the well known type of concrete paver employed for the construction of roads, streets, alleys, and the like.

In its practical embodiment, this invention deals with the problem of increasing the eliiciency of concrete paving machines, and concrete mixers generally, by providing means enabling the production of concrete by such machines at an increased speed of the action of the main operating units of the machine, resulting in materially lowering the cost of a unit of pavement of predetermined cubic area.

It is'obvious, that in, the operation of a machine of the type described, which according to present day construction, is a highly organized machine of correlated operating instrumentalities, the cost of putting a batch of concrete, soto-speak, through the machine, to the point of a finished mixed aggregate, depends primarily upon the length of the mixing cycle. Elucidation of this matter will be entered into in order to develop more fully the objective of this invention, which is to increase the productive capacity of the machine by lowering the cost of making a complete unit batch of mixed concrete therewith.

Time studies of the operation of concrete paving machines with the necessary .equipment for supplying aggregate materials thereto, reveal that where the mixing'cycle is approximately seventy-live seconds, and the cost and working conditions are approximately the same on the various jobs, a machine of twenty-seven cubic yard capacity, may produce about thirty-eight batches per operating hour, and the cost of producing each batch will approximate $1.05 per batch. Now if the requirements in the operation of such machine, according to specifications of a particular job, compel the use of a cycle of one-hundred-twenty-nine seconds for the mixing cycle, the rate of production may be expected to drop below twenty-four batches per hour so as to increase the cost of production about sixty percent, or to about $1.68 pei batch.

Now, it is the primary object of this invention to increase the mixing capacity ofa machine without modifying in any way the operating capacities of the charging andv discharging instrumentalities for supplying and emptying the mix- Serial No. 486,755

ing devices or receptacles proper. By doing this, I am enabled to run batches through my machine with accelerated speed, dependent upon the increase in the capacity. Thus in practice, and as an example, if my machine is of a single drum type wherein the mixing drum operates with a mixing cycle of seventy-live seconds, during sixty-seconds of which we will say the mixed aggregates are required to be mixed in the drum, the production of the machine will be about thirty-eight batches per operating hour. But I have found, in the carrying out of my invention, that I may double the mixing capacity of my machine by employing two drums of equal capacity to the single drum heretofore used, and I can double the operating capacity of my machine by mixing the batch in the first drum halt the time used for the mixing in a single drum machine, then transfer the batch from the first' drum to a second drum, and mix it the other half of the time required in the single drum machine.

The reason for the above, is due to the fact that the loading skip or charging instrumentality of the machine of the type I refer to, may be operated readily twice as fast and the discharging means by which the mixed materials are supplied to the boom bucket of the paver may readily be operated twice or more than twice as fast, in accomplishing its function.

Heretofore, therefore, the mixing cycle and the limited capacity of the single mixing drum, have held back the operation of the charging instrumentalities and the discharging instrumentalities, and correspondingly held down the capacity of the entire machine to produce an increased number 'of batches.

Of course, in the foregoing example, I have -only referred to my improvement as involving a doubling of the drum or mixing capacity of the machine, but the principle of my invention may involve the. tripling of such capacity. though for ordinary operating or working units, such as at present constructed for commercial use, the doubling of the capacity will suilice and will give excellent results by way of enabling the approximate cutting in half of the cost of production of a batch of mixing materials.

' With the foregoing, therefore, in view, as the principal objectives of my invention, I will refer to the accompanying drawings, in which:-

Figure 1 is a side elevation showing generally a known type of concrete paving machine, wherein, however. the structure is modified to provide mixing drums in tandem, one adapted to receive the unmixed aggregate materials, mix

them for a predetermined amount of time, after which they are passed to a second drum and mixed therein a predetermined amount of time, being thereupon supplied to the means for discharging the same into the boom or distributing bucket. This view illustrates diagrammatically instrumentalities of my invention for transferring theaggregatematerials from one drum to another in the continuous mixing cycle.

Figure 2 is a diagrammatic view of a chart or table showing the time factors and mode of mixing, incident to the operation of my machine, and illustrating clearly its capability of approximately doubling the productive capacity of the machine in mixed batches per hour.

Figure 3 is a somewhat enlarged diagrammatic view, bringing out a little more clearly certain of the instrumentalties between the drums arranged in tandem, the batchmetersassociated therewith, the power discharge instrumentalities under the control of the batchmeters, and mutually interlocked to act in proper timed relation, and the water supply means with skip controlled devices entering into the general combination of parts. y

Referring to Figure 1 of the drawings, the concrete paver illustrated is of a known type, and in the view, the various parts are diagrammatically shown as comprising a traction base 1, a main body frame 2, and an end boom 3 with its supported distributing bucket 4 adapted to travel outwardly and inwardly on theboom, the loading skip or charging instrumentality 5, and the mixing drums 6 and 7 disposed in tandem, end for end, the drum 7 arranged to receive the unmixed materials charged thereinto by the skip 5, and the drum 6 arranged to receive the batch of materials partly mixed by the drum 7 so as to nish the mixing operation respecting such materials, after which they are discharged from the drum 6 into the boom distributing bucket 4. Y

It is unnecessary to characterize in detail the instrumentalities utilized for operating the skip 5, the boom 3, the bucket 4 and the traction base 1, because all of these instrumentalities are well known in the art, and anyone versed in the art, is well acquainted with their mode of operation, and the means employed to that end.

Patents in the prior art showing and describing the general parts referred to, include Lichtenberg Patent No. 1,141,470, of June 1st, 1915, Robb Patent No. 1,660,301, of February 21st, 1928, and divers other issued Letters Patent.

The skip 5, as already known, is raised and lowered by means of cables 8, the action of which is controlled by a drum 9, and clutch instrumentalities for causing driving of said drum from the power plant of the machine so as to apply power to the cables and elevate the skip. Release of such clutch-means permits the skip 5 to gravitate to its downward position as shown in Figure 1, and the control of the said clutch instrumentalities is effected by a lever 10, seen in Figure 1.

Mounted upon the chassis of the machine are the drums 6 and 7, previously referred to, which are designed to take the place of the single drum usually employed today in such machines. The drums 6 and 7 will be of equal capacity with the single drum which has heretofore been employed so as to each handle the same quantity of aggregates to be mixed.

With this in mind, of course, it will be understood that the mixing capacity of my machine is doubled by the employment of the dual drum arrangement. Owing to this fact, it is clear that I am enabled touse two drums and cut in half the mixing period for the materials which may be required as to a single drum, through the simple process of mixing the materials in cach drum half of the time heretofore required for their admixture in a single drum. This being true, obviously, the materials handled by my machine may be caused to pass through the operating instrumentalities on the machine twice as fast, according to the general example which I am giving, and to which, of course, I do not need totbe restricted because the principle of the construction may be extended by varying the number of drums, and the time period during which the materials shall be admixed in each drum.

' Referring furtherv to the instrumentalities utilized in my present machine, I employ certain units known in the art as batchmeters, one batchmeter l1 coacting with the drum discharge instrumentalities 6 and timing the mixing period of said drum, and a second batchmeter 12 coacting with the drum 7 and timing the mixing action thereof. The batchmeters ll and 12 are associated with power discharge'devices 13 and 14 respectively, ythe same respectively cooperating with the drum units 6 and 7. The drum 6 is equipped with a discharge chute 15, and the drum 7 is equipped with a similar discharge chute 16. When the discharge chutes 15 and 16 are inclined upwardly and outwardly toward the left, or discharge ends of the drums, they are in non-discharging position, and certain types of said chutes may act as mixing means, though the latter function is not material to this invention. When said discharge chutes are inclined downwardly and outwardly toward the left ends of the drums, they are in discharging positions and capable of emptying the drums in the well known manner.

Now the units comprising the batchmeter 11, power discharge device 13, and chute 15, and the corresponding parts 12, 14 and 16 are of a type known in the art, and may be such as described and shown in the Robb patent, previously mentioned, or in the Webb Patent No. 1,628,378 of May 10th, 1927, and the Menningen Patent No. 1,648,144 of November 8th, 1927. Owing to the disclosures of said prior patents, the details of the constructions of the batchmeters, power discharge mechanisms, and chutes, are not treated particularly or illustrated fully herein. It is notable that at the top of the machine, the framework thereof carries' a trip rod 17, one end of which is adapted to be struck by 'the skip 5, when raised to its dotted line position of Figure 1, said rod 17 in this manner, setting the batchmeter 12, and performing possibly other functions to be hereinafter mentioned. For instance, the rod 17 also controls the shifting of a water valve 18, by which water is caused to be supplied to the mixer 7, which water will be a measured quantity and sufficient for the entire mixture preliminarily treated in the mixer 7, and later transferred for subsequent treatment to the mixer 6. A water tank19, partially illustrated, contains the water which is received from a suitable main in the customary well known way. The skip 5 carries at its pivotal axis 5a, an arm 20.

There areprovided certain hook-ups between the batchmeters and the power discharge mechanisms associated therewith. Included .among these is the provision on the power discharge 14 of Van arm 21 which has a peculiar function.

When the batchmeter 12 operates to set the power discharge 14 into action to turn the chute 16 to discharging position, the arm 21 is lowered so as to strike a bell crank lever 22, which is connected by a link 23, with the power discharge 13. The link 23 controls certain clutch mechanism of the power discharge 13 to throw said clutch mechanism into action whereby the power discharge will shift the discharge chute from a discharging positionto a non-discharging position when the said operation of the batchmeter 12 and power discharge mechanism 14 takes place. Again, the bell crank lever 22 has connection by a rod 24 with the batchmeter 11, so as to set the batchmeter 11 for its timing period control operation simultaneously with settingthe power discharge 13 into action to restore the chute 15 to non-discharging position.

The discharge chute 16 of the drum 7 can be restored to non-discharging position, after resuming a discharging position by any suitable means under batchmeter control as depicted in the Robb patent, previously identied, or as shown in Figure l and Figure 3, the skip 5 may accomplish this same action by the operation of its arm on the medially pivoted lever 25.

The lever 25 is connected by a rod 26 to a bell crank 27 connected by a rod 28 to the power discharge mechanism 14. Therefore, as the skip rises, the parts 20, 26, 27 and 28 will operate the power discharge 14 to cause the discharge 16 to assume a non-discharging adjustment.

With the foregoing in mind, a cycle of operation of the machine may be given as follows. Let it be assumed that the batchmeter 12 has been set to control mixing in the drum 7 for a period of thirty seconds. Let us assume also, that the drum 7 contains its full 'quantity of aggregates and the period of mixing has now elapsed and the batchmeter 12 is tripped by its timing mechanism, its bell or signal operating at the same time. The tripping of the batchmeter 12 releases and trips the power discharge unit 14 which automatically turns the discharge chute 16 to discharge position. Since the discharge unit 14 is connected with the skip raising lever 10 by the connection 10a, this lever 10 will be simultaneously operated to engage the skip hoisting clutch and the power unit of the machine will cause the skip 5 to be raised by winding up the cables 8 connected thereto.

- The power discharge unit 14, when operated to perform the discharge of the drum '7, and cause the raising of the skip 5, acts to perform the additional functions of tripping the power discharge unit 13 of drum 6. The discharge chute 15 is, in this manner, automatically turned to its non-discharging position. At the same time, through the provision of the rod 24, the power discharge unit 14 acts to set the batchmeter 11 for controlling the mixing in the drum 6 and the cycle of thirty seconds for mixing in the latter drum, will be thus predetermined and controlled.

As the materials have now been transferred from the drum 7 to the drum 6, and are being mixed in the drum 6, the skip 5 is rising to its elevated position, and recharging the drum 7 with a fresh batch of concrete aggregates. The rising of the skip not only charges the drum 7, but actuates the rod 17 to reset the batchmeter 12 which was previously tripped, as described. At the same time, either through the batchmeter 12, or by means of the parts 25, 26, 27 and 28, the skip will cause the discharge chute 16 of drum 7 to be` turned back to its non-discharging` position, a, necessary vadjustment to prevent thev freshly charged aggregates from passing right out of the drum, as will be readily obvious.' Like- Wise, when the skip 5 has been elevated to its position for charging the drum 7, the skip hoist clutch under the control of the lever 10 is disengaged so asto discontinue the upward movement of the skip as it reaches its dotted line position of Figure 1, and similarly there is applied the usual brake provided as an adjunct of the skip hoist clutch mechanism whereby the skip Will be held in its upward dotted line'position'.

Thereafter, the skip 5 is lowered under the control aof the operator who manipulates the lever 10 for such purpose, and the water which was turned on by the actuation of the rod 17 by the skip as the skip moved upwardly according to the previous description, is now turned off' by the downward movement of the skip in the well known manner, as illustrated for instance, inthe Robb patent.

The use of the clutch and brake instrumen-.- talities for the elevating of the skip to charge the drum 7, and the brake, to hold it elevated, pendingA the assumption of control by the operator, are well known features of machines of the type of my invention. Of course, as soon as the time period of mixing in the mixer 6 has elapsed, said period being thirty seconds in the present example of construction and operation described, the batchmeter 11 will trip off and automatically cause the action of the power discharge 13 to turn the chute 15 to a discharging position and thereby discharge the contents of the mixer 6 into the distributing bucket 4. Later, the discharge chute 15 will be restored to nondischarge position by the action of the parts 21 and 23, Vas previously set forth, so that I have now carried the operation of the machine through a complete mixing cycle.

In conclusion, I might note that by mixing cycle, I have in mind three phases of the machines operation :-First, the time required to get the batch into the drum; second, the mixing time, or the time during which the materials must be in the drum according to the specifications of the job; and third, the time required to get the mixed batch or batches out of the drum, or drums.

With my particular invention, the transfer of the mixed materials from the drum 7 to the drum 6 involves a mere step in the agitation of the materials, so that for all practical purposes, their mixture in the two drums 6 and 7 may be considered a single mixing cycle, even though the periods of time of the mixing in the two drums follow each other in successive order.

,Having in view the foregoing, using the same charging instrumentalities, including the skip 5 and distributing instrumentalities, including the bucket 4, as heretofore proposed, I am enable by my invention, according to the example given,

to double the mixing capacity of my entire machine, and cut in half the cost of production of a complete mixed batch of concrete aggregates. Obviously, the proportion of time which may be saved by the use of the principle of my invention, depends upon the amount of increase of the mixing capacity of the machine. Moreover, it is quite apparent that according to the invention proposed, the machine is practically entirely automatic because the batchmeter 12 acts not only to control the period of mixing of the batch in the drum 7. but also to automatically transfer this batch to the succeeding drum 6. Moreover, the batchmeter 12 indirectly controls the entire action not only of the charging of the drum 6, but its discharging and the time of mixing in the drum 6, through the control of the batchmeter 11 and the power discharge unit 13.

Figure 3 of the drawings shows the means intermediate the power discharge units 13 and 14, and the respective chutes'l and 16 for tilting the chutes from discharging to non-discharging positions, and vice versa. This means is in accordance with the prior art patents of Webb and Menningen hereinbefore referred to and generally includes links a, connected with rocker levers b, the levers b being attached by the links c direct to the chutes. Of course, it is obvious that whether the units 13 or 14 are on the lower partof the frame or the upper part, is something quite irnmaterial;

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:-

1. In a concrete mixing machine, in combination, a support, a charging device, a plurality or mixing drums carried by the support, one of which is arranged to receive unmixed aggregates from the charging device, a discharge for said one of the mixing drums, a discharge for the other of said mixing drums, batchmeters associated with the mixing drums, one of said batchmeters being settable from the charging device and controlling 'the time of mixing of materials in the drum charged from said charging device, the other batchmeter being settable from the discharging device of the last mentioned drum for, controlling the time of mixing of the materials in the second drum, a discharge operating device for each drum, and connections between each discharge operating device and the batchmeter associated with its drum, the discharge operating device of the drum charged by the charging device being arranged to discharge the contents of said drum into the second drum under control of the batchmeter associated with the rst drum.

2. In a concrete mixing machine, in combination, a support, a charging device, a plurality of mixing drums carried by the support, one of which is arranged to receive unmixed aggregates from the charging device, a discharge for said one of the mixing drums, a discharge for the other of said mixing drums, batchmeters associated with the mixing drums, one of said batchmeters being settable from the charging device and controlling the time of mixing of materials in the drum charged from said charging device, the other batchmeter controlling the time of mixing of the materials in the second drum, a discharge operating device for each drum, connections between each discharge operating device and the batchmeter associated with its drum, the discharge operating device of the drum charged by the charging device being arranged to discharge the contents of said drum into the second drum, means controlled from the batchmeter of the rst drum for causing automatic action of the discharge operating device thereof, and means controlled by the discharge operating device of the first drum for setting the batchmeter of the second drum.

3. In a concrete mixing machine, in combination, a support, a plurality of drums mounted thereon for mixing concrete materials, a charging device for one of said drums, transfer mechanism between the two drums for transferring the contents of said one drum into the other drum, a discharge device for the last mentioned drum, batchmeters for both drums, one of said batchmeters controlling the automatic action of said transfer mechanism, the other of said batchmeters controlling the discharge of the second drum, and mechanism initiated in its operation by one of the batchmeters for causing. setting of the other batchmeter.

4. In a concrete mixing machine, in combination, a support, a drum charging device thereon, rst and second mixing drums carried thereby, a batchmeter for each `mixing drum, a power discharge operating device for each drum, a power discharge for each drum adapted to be actuated by its associated power discharge operating device, the power dischargesof the rst drum being arranged to transfer the contents of the first drum to the second drum, the power discharge of the second drum being adapted to discharge or empty the second drum, means for setting the batchmeter of the rst drum from the charging device, instrumentalities for setting the batchmeter of the seconddrum from the power discharge operating device of the rst drum, and means intermediate the batchmeter of the second drum and the power discharge operating device for the second drum for rendering the said power discharge operating device operable under the control of the second drums batchmeter to empty the second drum.

ERICH H. LICHTENBERG. 

